Muffler housing

ABSTRACT

Crimps in the interlock joint between the ends of a muffler shell and the headers add sufficient strength to insure failure in the longitudinal shell seam in the event of excessive internal pressure.

United States Patent 11 1 1111 3,903,987

Brown et a1. 1 1 Sept. 9, 1975 [54] MUFFLER HOUSING 3,103,256 9/1963 Deremer 181/54 3,248,791 5 1966 P 181 54 [75] Inventors: Howard L. Brown; James F. Mowat, 3 310 86] $1967 az Sg 29/5/05 both of Michigan Center, Mich- 3,311,139 3/1967 Powers 181/54 3,485,319 12/1969 Balluff 181/54 [73] Asslgnee. Tenneco Inc., Racine, Wis. 3643760 2/1972 Hubbel 181/54 [22] Filed; Feb, 20, 1973 3,682,270 8/1972 Haren 181/54 [21] Appl. No.: 333,955

Primary Examiner-Stephen J. Tomsky Assistant Examiner-Vit W. Miska [52] [1.8. CI 181/61; 181/35 C Attorney, Agent, or Firm Harness, Dickey & Pierce [51] Int. Cl.. F0ln 7/18 [58] Field of Search 181/53, 54; 29/157 R, 505,

29/521, 41, 49, 61, 62, 63, 72, 35 C [57] ABSTRACT Crimps in the interlock joint between the ends of a [56] References Cited muffler shell and the headers add sufficient strength to UNITED STATES PATENTS insure failure in the longitudinal shell seam in the 1,995,364 3/1935 Shatkin 29/505 event of excessive internal pressure. 2,212,715 8/1940 Levan 1 1 29/505 2.685,]29 8/1954 Myers, Jrw ,1 29/505 6 Claims, 4 Drawing Figures \2 X 4/ u x 4/ 1-1 -11 x 1 1-1 1 1 Z 1 1 1 x x I I I I p 7 J m, j x Z I v j l V L; 1- ']rrif Q lit-'1:

1 ll 4 II '11 1 5 1|. .1 l 1 I 1 1+ 1 rr y; x

MUFFLER HOUSING BRIEF SUMMARY OF THE INVENTION It is the purpose of this invention to provide a muffler housing constructed so that failure due to excessive internal pressure will occur at a predetermined location in the muffler, namely, the longitudinal shell seam. The invention provides simple means, preferably crimps or flats, to strengthen the header-to-shell joints so that blow-out occurs in the seam instead of one of the joints.

When failure occurs in the header-to-shell joints, it is uncontrolled in that its location cannot be predicted. In automotive exhaust systems, hot exhaust gas escaping through joint failure can damage adjacent equipment such, for example, as plastic tubing or electrical wiring. By confining failure of the longitudinal shell seam, as is done in the muffler housings of this invention, the exhaust system designer can so arrange the muffler as to predetermine that failure will not result in undesired damage due to the escaping hot gas.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross section through a typical exhaust muffler having a housing embodying the invention, the gas flow tubes being rotated into the plane of the section to facilitate illustration;

FIG. 2 is an end view. partly broken away and in section, taken from the right or outlet end of the muffler;

FIG. 3 is an enlarged section along the line 3-3 of FIG. 2; and

FIG. 4 is an enlarged section along the line 44 of FIG. 2.

In the drawing, the symbol x" indicates a spotweld or the equivalent.

DESCRIPTION OF THE INVENTION A muffler I has a housing 3 that comprises an oval tubular shell 5 whose opposite ends are closed by inlet and outlet headers 7 and 9. The headers are secured to the shell by conventional interlocked joints 11 wherein the ends of the shell and the peripheries of the headers are overlapped and reversely bent together. The shell 5 is formed from a flat sheet which is turned into a tube and the opposite longitudinal edges 13 overlapped and secured together in a plain (uncorrugated) lock seam I5 of a type conventionally used in the art.

The silencing structure inside the shell 5 may take various specific forms. As illustrative of such structure, the housing 3 contains two transverse partitions l7 and I9, spotwelded to shell 5, which subdivide the interior into three chambers 21, 23, and 25. The partition 17 has three annular necks 27, 29, and 31 and the partition 19 has three necks 33, 35, and 37 longitudinally aligned respectively with these necks. Tubes 39, 41, and 43 extend through and are supported in the respective aligned pairs of necks 27 33, 29 35, and 31 37, the outer end of tube 39 actually slidably fitting inside of inlet bushing 45 which is spotwelded to neck 27 and the outer end of the tube 41 actually slidably fitting inside of outlet bushing 47 which is spotwelded to neck 35. The bushing 45 is supported in and spotwclded to a neck 49 in header 7 and the outlet bushing 47 is sup ported in and spotwelded to a neck 5] in outlet header 9. The inlet tube 39 has patches of louvers 53 opening into the space between shell 55 and the outside of the tube to form spit chambers 57 and 59 for attenuating high frequencies and roughness. Tube 41 has a similar spit chamber 61 as well as a louver patch 63 opening into chamber 23. Tube 43 has a louver patch 65 opening into chamber 23. The tube 43 also has a portion 67 extending into chamber 25.

A protective wrap 69 of asbestos or equivalent insu lative material extends around the outside of shell 5 along most of its length and is held in place by a metal outer wrap 71 that is formed from flat metal whose longitudinal edges are united at 73 in a simple (uncorrugated) lock seam joint that is adjacent shell lockseam 15. The lockseams l5 and 73 are shown in FIG. 2 at the bottom of the muffler 1, it being contemplated that the muffler will be mounted in use with its major axis vertical.

In a typical muffler the headers 7 and 9 might be made of 0.060 to 0.075 inch low carbon steel material, the shell 5 from 0.036 inch low carbon steel stock, and the cover 71 from 0.018 inch low carbon steel stock. Since the joints 1] contain the thicker header material and all materials are substantially the same, they have the potential of being formed into stronger mechanical connections than seams l5 and 73. This is insured by means of the present invention according to which portions, at least, of the joints 1 l are crushed, flattened, or deformed to materially increase the holding power and blow-out resistance of the joint. A preferred method of doing this is illustrated by the V-shaped wedge type indentations 75 shown in FIGS. 2 and 4. These are illustrated as being formed along the two major sides of the oval and can be readily accomplished in conventional press forming equipment, using a suitable punch and pad. This is done, of course, after the muffler is substantially completely assembled. The wedge indentations serve to tightly interlock and unite the ends of the shell 5 and the peripheries of the header, as seen in FIG. 4. The net results is that the joints 1] are reliably stronger than the seams 15 and 73 so that blow-out, if any, occurs in the seams where the direction of flow of escaping gas can be predicted and therefore controlled.

Modifications in the specific details illustrated may be made without departing from the spirit and scope of the invention.

We claim:

1. A muffler comprising a tubular metal shell having a longitudinal seam, metal headers closing opposite ends of the shell, the ends of the shell and the peripheries of the headers being united in interlocked joints of reversely bent metal, portions at least of said joints being flattened and compressed together to increase the strength of said joints so that said joints have greater resistance to blow-out under excessive internal pressure than does the longitudinal seam, said headers having inlet and outlet openings respectively, and gas flow and silencing structure in said shell connecting said inlet and outlet.

2. A muffler as set forth in claim 1 wherein said flattened portions are wedge shaped.

3. A muffler as set forth in claim 2 wherein said shell is oval and a plurality of said wedge shaped indentations are formed on the two major sides of the shell on opposite sides of the major axis.

4. A muffler as set forth in claim 3 including an outer metal wrap of metal around Said shell, said wrap having a seam adjacent the shell seam and of less strength than Said joints.

5. A muffler as set forth in claim 4 wherein said header is formed of metal that is thicker than said shell seams are lockseams comprising reversely bent interfitand said shell is formed of metal that is thicker than ting longitudinal edges of the metal. said wrap.

6. A mufiler as set forth claim 1 wherein said UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 987 Dated September 9, 1975 Inventor(s) Howard L. Brown and James F. Mowat, Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 4, C01. 2, line 67, after "a" insert separate Claim 6, C01. 3, line 4, "1' should be 5 Signed and Scaled this twenty-fifth Day Of May 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (ummissinner nj'larems and Trademarks 

1. A muffler comprising a tubular metal shell having a longitudinal seam, metal headers closing opposite ends of the shell, the ends of the shell and the peripheries of the headers being united in interlocked joints of reversely bent metal, portions at least of said joints being flattened and compressed together to increase the strength of said joints so that said joints have greater resistance to blow-out under excessive internal pressure than does the longitudinal seam, said headers having inlet and outlet openings respectively, and gas flow and silencing structure in said shell connecting said inlet and outlet.
 2. A muffler as set forth in claim 1 wherein said flattened portions are wedge shaped.
 3. A muffler as set forth in claim 2 wherein said shell is oval and a plurality of said wedge shaped indentations are formed on the two major sides of the shell on opposite sides of the major axis.
 4. A muffler as set forth in claim 3 including an outer metal wrap of metal around said shell, said wrap having a seam adjacent the shell seam and of less strength than said joints.
 5. A muffler as set forth in claim 4 wherein said seams are lockseams comprising reversely bent interfitting longitudinal edges of the metal.
 6. A muffler as set forth in claim 1 wherein said header is formed of metal that is thicker than said shell and said shell is formed of metal that is thicker than said wrap. 